My Network Not Shown as available

[#1]

Somebody in the house was able to connect to my wi fi service, but I changed the Thomson router to another Thomson router and now in the 'Available networks' shown on their XP desktop lists all of my neighbours' as having good to reasonable signal strength, but my Plusnet service is shown as having no signal at all. I've tried deleting the service and then re-searching for it but it still shows as zero signal for my Plusnet service. My desktop and 2 other laptops are fine.

[#2]

I would try changing the wireless channel on the router, especially if it is set to 12 or 13 at present.

[#3]

I did think of that but I went onto the router gateway page and went through the various options but wasn't sure where to find it. Could you point me in the right direction? Thanks.